scholarly journals The Testing Equipment to Study Heat Transfer through a Frame-Panel Enclosure Structure Fragment

2016 ◽  
Vol 73 ◽  
pp. 02022
Author(s):  
Vladimir Borzykh ◽  
Pavel Mikhailovt ◽  
Igor Shalagini
Keyword(s):  
Heat Transfer ◽  
Testing Equipment ◽  
Structure Fragment ◽  
Study Heat Transfer

High Speed Twin-Roll Casting of Al-Mg Alloys

2010 ◽  
Vol 154-155 ◽  
pp. 1544-1548 ◽  
Author(s):  
Kosuke Komeda ◽  
Ryoji Nakamura ◽  
Shinji Kumai
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
High Speed ◽  
Aluminum Alloy 5182 ◽  
Roll Casting ◽  
Twin Roll Caster ◽  
Deep Drawing Test ◽  
Study Heat Transfer ◽  
Twin Roll ◽  
Steel Rolls

The disadvantages of the conventional twin-roll caster for aluminum alloy are low casting speeds and limited choices of alloys that are castable by this processing. It is known that strip casting of aluminum alloy 5182 is very difficult because of their wider freezing zones. The vertical-type high-speed twin-roll caster used in the present study was devised to overcome these disadvantages. Features of the high speed twin roll casters are as below. Mild steel rolls were used in order to increase the casting speed and to be made at a lower equipment cost. Roll coating is produced in casting of Al-Mg alloy. Therefore lubricant, that resists heat transfer, was not used in the present study. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metalography, a tension test, and a deep drawing test.

Direct Numerical Simulation of Particle Heat and Mass Transfer in a Fluidized Bed

2014 ◽  
Author(s):  
Zhi-Gang Feng ◽  
Adam Roig
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Fluidized Bed ◽  
Immersed Boundary Method ◽  
Fluid Velocity ◽  
Temperature Fields ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Study Heat Transfer

We have developed a Direct Numerical Simulation combined with the Immersed Boundary method (DNS-IB) to study heat transfer in particulate flows. In this method, fluid velocity and temperature fields are obtained by solving the modified momentum and heat transfer equations, which result from the presence of heated particles in the fluid; particles are tracked individually and their velocities and positions are solved based on the equations of linear and angular motions; particle temperature is assumed to be a constant. The momentum and heat exchanges between a particle and the surrounding fluid at its surface are resolved using the immersed boundary method with the direct forcing scheme. The DNS-IB method has been used to study heat transfer of 1024 of heated spheres in a fluidized bed. By exploring the rich data generated from the DNS-IB simulations, we are able to obtain statistically averaged fluid and particle velocity as well as overall heat transfer rate in a fluidized bed.

A Computational Approach to Study Heat Transfer Enhancement in Film Boiling due to the Addition of Surfactants

2016 ◽  
Author(s):  
Kannan N. Premnath ◽  
Farzaneh Hajabdollahi ◽  
Samuel W. J. Welch
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Surfactant Concentration ◽  
Computational Approach ◽  
Film Boiling ◽  
Two Phase ◽  
Diverse Range ◽  
Study Heat Transfer ◽  
Interfacial Surfactant ◽  
Adsorption Desorption

Two-phase flows involving phase change are ubiquitous in a diverse range of scientific and technological applications. There has been great recent interest in the enhancement of boiling heat transfer processes by means of additives such as surfactants. Surfactants can influence boiling through convection currents in the bulk fluids as a result of changes in the surface tension caused by local surfactant concentration due their adsorption/desorption from the bulk regions. This can result in changes in bubble release patterns and higher heat transfer rates if such changes lead to higher rate of vapor formation. We intend to study this effect in the context of film boiling. Our computational approach augments the CLSVOF method with bulk energy and diffusion equations along with a phase change model and an interface surfactant model. The challenge here is to accurately calculate the tangential gradients of the interfacial surfactant concentration in the presence of discontinuous bulk concentration gradients near the interface. We discuss a simplified model in which the interfacial surfactant concentration is always in equilibrium with the changing bulk concentrations and then present validation results to assess the accuracy of this approach. Finally, initial studies of surfactant enhanced film boiling will be presented and interpreted.

scholarly journals Failure Analysis of Heat Exchangers with a Valid CFD Simulation

2021 ◽  
Author(s):  
Ádám Sass ◽  
Alex Kummer ◽  
Zsolt Ulbert ◽  
Attila Egedy
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cfd Simulation ◽  
Flow Characteristics ◽  
Industrial Process ◽  
Infrared Camera ◽  
Stable Operation ◽  
Tubular Heat Exchanger ◽  
Surface Measurements ◽  
Study Heat Transfer

Energy efficiency, safety and stable operation of units are the most crucial aspects in every industrial process. In this study, Computational Fluid Dynamics (CFD) simulations were used to study heat transfer in a laboratory-sized tubular heat exchanger. A partly 2D axisymmetric and mainly 3D model of the heat exchanger was created and validated with several simulation in different operating points of heating capacity and volume flow. The results of the simulations were compared to experimental data to validate the model. The inlet and outlet temperatures were measured with Pt100 temperature probes, and the surface temperatures were measured with an infrared camera. The heat transfer coefficient was determined based on the surface measurements The validated model was applied for the investigation of performance losses of heat exchanger due to fouling caused by particle deposits along the tube which caused reduced heat transfer surface or performance and a failure of heating wire which caused reduced heating performance, hence altered heat and flow characteristics through the equipment. The results provide useful information not only in the design processes but the operational lifetime as well.

scholarly journals High-order fluxes in heat transfer with phonons and electrons: application towavepropagation

2021 ◽  
Vol 477 (2253) ◽  
pp. 20210392
Author(s):  
I. Carlomagno ◽  
M. Di Domenico ◽  
A. Sellitto
Keyword(s):  
Heat Transfer ◽  
Irreversible Thermodynamics ◽  
High Order ◽  
Lattice Vibrations ◽  
Thermal Waves ◽  
Local Effects ◽  
Proposed Model ◽  
Non Local ◽  
Study Heat Transfer ◽  
Heat Carriers

We propose a theoretical model to study heat transfer at the nanoscale by means of high-order thermodynamic fluxes. The model is fully compatible with the model of heat transfer of extended irreversible thermodynamics, represents a generalization of the Guyer–Krumhansl proposal (Guyer & Krumhansl 1966 Phys. Rev. 148 ) and is able to deal with relaxational and non-local effects. It also accounts for the role played by the different heat carriers (electrons and/or lattice vibrations) and captures different heat-carrier temperatures. The proposed model is hyperbolic and is used to investigate the propagation of thermal waves.

Effect of Wavy Wall and Plate Bifurcations On Heat Transfer Enhancement in Microchannel

2021 ◽  
Author(s):  
Sathish Kumar D ◽  
Jayavel S
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Working Fluid ◽  
Thin Wall ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Entropy Generation Number ◽  
Transfer Characteristics ◽  
Overall Performance ◽  
Study Heat Transfer

Abstract Miniaturization of electronic components requires compact and effective cooling techniques to dissipate large heat flux without significant increase in pumping power. Microchannel heat sink with liquid as working fluid is a suitable technique for the purpose. In the present study, heat transfer characteristics in presence of vertical bifurcation placed in the downstream of the microchannel passage is studied numerically. Six types of bifurcating plates are considered under two categories: (i) thick-plate and (ii) wavy thin-wall. Water is taken as the working fluid and the flow rate has been varied in the Reynolds number range, 100 = Re = 1000.The effect of bifurcations on pressure drop, heat transfer and the overall thermal resistance are analyzed and compared with those of plane microchannel without bifurcation. The numerical results show that the usage of bifurcation in the microchannel reduces the overall thermal resistance. Field synergy number, entropy generation number and hydro-thermal performance index are calculated to quantify the overall performance improvement in the microchannel with bifurcations. Constant wavy thin-wall bifurcation has been found to improve the overall performance of the microchannel. The detailed geometry of the bifurcation, the resulting convective heat transfer characteristics and percentage improvement in the performance are reported.

Analytical accuracy of the one dimensional heat transfer in geometry with logarithmic various surfaces

2014 ◽  
Vol 4 (4) ◽  
Author(s):  
A. Vahabzadeh ◽  
M. Fakour ◽  
D. Ganji ◽  
I. Rahimipetroudi
Keyword(s):  
Heat Transfer ◽  
Homotopy Perturbation Method ◽  
Adomian Decomposition Method ◽  
Variational Iteration Method ◽  
Physical Parameters ◽  
One Dimensional ◽  
Adomian Decomposition ◽  
Analytical Accuracy ◽  
Study Heat Transfer ◽  
The One

AbstractIn this study, heat transfer and temperature distribution equations for logarithmic surface are investigated analytically and numerically. Employing the similarity variables, the governing differential equations have been reduced to ordinary ones and solved via Homotopy perturbation method (HPM), Variational iteration method (VIM), Adomian decomposition method (ADM). The influence of the some physical parameters such as rate of effectiveness of temperature on non-dimensional temperature profiles is considered. Also the fourth-order Runge-Kutta numerical method (NUM) is used for the validity of these analytical methods and excellent agreement are observed between the solutions obtained from HPM, VIM, ADM and numerical results.

Numerical Analysis of Fluid Flow and Heat Transfer of Flow Between Parallel Plates Having Rectangular Shape Micromixer

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Sudip Shyam ◽  
Aparesh Datta ◽  
Ajoy Kumar Das
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Secondary Flows ◽  
Parallel Plates ◽  
Maximum Enhancement ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Study Results ◽  
Study Heat Transfer

In this study, heat transfer and fluid flow of de-ionized water in two-dimensional parallel plates microchannel with and without micromixers have been investigated for various Reynolds numbers. The effects of heat transfer and fluid flow on height, diameter of micromixer, and also distance between the two micromixers are carried out in the study. Results showed that the diameter of the micromixer does not have much effect on heat transfer with a maximum enhancement of 9.5%. Whereas heat transfer gets enhanced by 85.57% when the height of the micromixer is increased from 100 μm to 400 μm, and also heat transfer gets improved by 11.45% when sb2 is increased from 4L to 5L. The separation and reattachment zone at the entry and exit of the micromixer cause the increase in heat transfer with the penalty of pressure drop. It is also found that increase of Reynolds number increases the intensity of the secondary flows leads to rapid increase in heat transfer and pressure drop. Finally, the optimized structure of micromixer is found out based on maximum heat transfer and minimum pressure drop.

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